The present invention relates to testing of wireless devices, and in particular, to controlling delays of multiple radio frequency (RF) signals transmitted to a RF signal transceiver device under test (DUT) to test its ability to determine relative times of arrival (ToAs) or angles of arrival (AoAs) of such delayed RF signals.
Many of today's electronic devices use wireless signal technologies for both connectivity and communications purposes. Because wireless devices transmit and receive electromagnetic energy, and because two or more wireless devices have the potential of interfering with the operations of one another by virtue of their signal frequencies and power spectral densities, these devices and their wireless signal technologies must adhere to various wireless signal technology standard specifications.
When designing such wireless devices, engineers take extra care to ensure that such devices will meet or exceed each of their included wireless signal technology prescribed standard-based specifications. Furthermore, when these devices are later being manufactured in quantity, they are tested to ensure that manufacturing defects will not cause improper operation, including their adherence to the included wireless signal technology standard-based specifications.
Testing of such wireless devices typically involves testing of the receiving and transmitting subsystems of the device under test (DUT). The testing system will send a prescribed sequence of test data packet signals to a DUT, e.g., using different frequencies, power levels, and/or signal modulation techniques to determine if the DUT receiving subsystem is operating properly. Similarly, the DUT will send test data packet signals at a variety of frequencies, power levels, and/or modulation techniques for reception and processing by the testing system to determine if the DUT transmitting subsystem is operating properly.
For testing these devices following their manufacture and assembly, current wireless device test systems typically employ testing systems having various subsystems for providing test signals to each device under test (DUT) and analyzing signals received from each DUT. Some systems (often referred to as “testers”) include, at least, one or more sources of test signals (e.g., in the form of a vector signal generator, or “VSG”) for providing the source signals to be transmitted to the DUT, and one or more receivers (e.g., in the form of a vector signal analyzer, or “VSA”) for analyzing signals produced by the DUT. The production of test signals by the VSG and signal analysis performed by the VSA are generally programmable (e.g., through use of an internal programmable controller or an external programmable controller such as a personal computer) so as to allow each to be used for testing a variety of devices for adherence to a variety of wireless signal technology standards with differing frequency ranges, bandwidths and signal modulation characteristics.
Referring to FIG. 1, a typical testing environment 10a includes a tester 12 and a DUT 16, with test data packet signals 21t and DUT data packet signals 21d exchanged as RF signals conveyed between the tester 12 and DUT 16 via a conductive signal path 20a, typically in the form of co-axial RF cable 20c and RF signal connectors 20tc, 20dc. As noted above, the tester typically includes a signal source 14g (e.g., a VSG) and a signal analyzer 14a (e.g., a VSA). The tester 12 and DUT 16 may also include preloaded information regarding predetermined test sequences, typically embodied in firmware 14f within the tester 12 and firmware 18f within the DUT 16. The testing details within this firmware 14f, 18f about the predetermined test flows typically require some form of explicit synchronization between the tester 12 and DUT 16, typically via the data packet signals 21t, 21d. Alternatively, testing may be controlled by a controller 30 which may be integral to the tester 12 or external (e.g., a programmed personal computer) as depicted here. The controller 30 may communicate with the DUT 16 via one or more signal paths (e.g., Ethernet cabling, etc.) 31d to convey commands and data. If external to the tester 12, the controller 30 may further communicate with the tester 12 via one or more additional signal paths (e.g., Ethernet cabling, etc.) 31t to convey additional commands and data.
Referring to FIG. 2, an alternative testing environment 10b uses a wireless signal path 20b via which the test data packet signals 21t and DUT data packet signals 21d may be communicated via respective antenna systems 20ta, 20da of the tester 12 and DUT 16.
Ordinarily when testing a wireless device (e.g., wireless fidelity (WiFi), Bluetooth, Zigbee, Z-Wave or similar device) with a tester, once communications between tester and DUT have been established, the tester and DUT will execute a test flow during which the tester or controller controls the behavior of the DUT (e.g., by executing control commands via driver software associated with the DUT). Commands may include instructing the DUT to receive test packets from the tester, or to transmit packets to the tester. The characteristics of the packets may also be controlled, such as power level, frequency, data rate, modulation, etc.
Currently, more wireless devices are including location-awareness capabilities for determining their physical location. An internal wireless positioning system uses localization information available from various internal sensors as well as measuring certain characteristics of signals received from external sources. For example, a relative location of a device may be estimated by measuring incoming signal parameters such as time-of-arrival (ToA) or angle-of-arrival (AoA) of the incoming signals. However, performing accurate and time-efficient testing of such capabilities has proven challenging in production testing environments. For example, the time delay resolution for AoA testing in mobile applications is usually in the range scale of sub-tens of picoseconds (psec), which is a difficult signal to generate. Also, one test technique involves over the air (OTA) testing. However, an OTA test requires large distances between the signal source and device under test (DUT) to ensure reception of a plane signal wave at the receiving antenna. Further, testing of different delays and incident angles requires changing such distance(s) and reorientation (e.g., rotation) of the DUT relative to the source. Both of these requirements are difficult to implement in a test environment. Accordingly, in view of increasing demand by users of such devices for accurate positioning data, a need exists for systems and methods to perform such testing.